1. Field of the Invention
This invention relates to a method of making a polymeric arched endless power transmission belt and to a belt made employing such method.
2. Prior Art Statement
In applications where a polymeric endless power transmission belt is operated under comparatively high operating load it is important that such belt have substantial stiffness or rigidity transverse its longitudinal axis to assure that such belt does not "dish" or is stressed into a downwardly bowed configuration under load. This dishing results in abnormally high stresses in the edge cords of the belt causing breaking thereof and premature failure of such cords and the overall belt. Dishing also causes high heat buildup within elastomeric portions of the belt and this heat buildup degrades the adhesive bond between belt components as well as degrading the components themselves resulting in premature failure. There is also a tendancy for such a highly loaded belt to be subjected to unusually high stresses in the outer portion of its compression section, especially when operating around sheaves of comparatively small diameter, and such stresses cause cracks which propagate into the body of the belt causing belt failure.
It is known in the art to provide a method of making a polymeric arched endless power transmission belt with the method comprising the steps of disposing in tubular form a plurality of uncured belt-defining layers wherein the layers are adapted to define corresponding sections of the belt and curing the layers in a controlled environment to define the belt having an arched configuration and as disclosed in U.S. Pat. No. 4,019,399 and wherein the arched configuration is for the purpose of minimizing dishing.
It is also known to provide a method of making an endless power transmission belt which utilizes randomly arranged elongate fibers which are disposed substantially perpendicular to the longitudinal axis of the belt to increase the transverse or lateral stiffness of the belt and as disclosed in U.S. Pat. No. 3,416,383 for a typical V-belt of trapezoidal cross section. A so-called central neutral axis belt is disclosed in U.S. Pat. No. 3,987,684 which uses fiber-loaded layers coperating with fabric layers to increase its transverse rigidity.
It is also known to provide a method of making a toothed belt of substantially trapezoidal cross-sectional configuration which has the usual compression section and wherein the outer portion of the compression section has a toothed configuration which is provided with a resilient compound between the teeth thereof. The resilient compound is softer than the rest of the belt and is used for providing an increased traction area and forming a yielding surface which also reduces noise; as disclosed in U.S. Pat. No. 2,062,568.
Finally, it is known in the art to provide a method of making a comparatively high load capacity endless power transmission belt which employs stress-relief slits in its compression section as disclosed in U.S. Pat. No. 3,995,507, for the purpose of avoiding high stresses and cracks in the compression section and overall belt.
It is an object of this invention to provide an improved method of making a polymeric arched endless power transmission belt.
It is another object of this invention to provide an improved belt.
Other aspects, embodiments, objects, and advantages of this invention will become apparent from the following specification, claims, and drawings.